mycophenolate mofetil (CellCept)

Mycophenolic acid is an immunosuppressive drug. It is indicated for the prophylaxis of organ rejection in patients receiving kidney, heart, or liver transplants. mycophenolate mofetil should be used concomitantly with cyclosporine and corticosteroids.

Mycophenolate mofetil is a prodrug (inactive form) of mycophenolic acid (MPA). Following oral administration, mycophenolate mofetil is rapidly absorbed and hydrolyzed (converted) to MPA. MPA is the active metabolite which has pharmacological activity.

MPA is a strong, reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH). IMPDH plays a critical role in the production of DNA. T and B lymphocytes (immune cells) are heavily dependent on the activity of IMPDH to make DNA to proliferate, whereas other cells can use alternative pathways. In patients who have received transplanted organs, the recipient's immune system attacks the transplanted organ because the body perceives it as foreign or harmful. MPA decreases the activity of the immune system by inhibiting the proliferation of immune cells that attack the transplanted organ. Mycophenolate is used with other medications that also inhibit the rejection of transplanted organs such as cyclosporine (Sandimmune, Gengraf, Neoral) and corticosteroids.

Mycophenolate mofetil was approved by the U.S. FDA on May 3, 1995.

Common side effects include:

• diarrhea,
• vomiting,
• pain,
• pain in the stomach area,
• high blood pressure, and
• swelling of the lower legs, ankles, or feet.

It may also cause:

• infection,
• blood infection,
• sore throat,
• low white and red blood cell count, and
• low blood platelets (thrombocytopenia).

Mycophenolate mofetil should be given to patients as soon as possible following organ transplantation. Mycophenolate mofetil is recommended to be administered on an empty stomach, except in stable renal transplant patients in whom it can be administered with food if necessary.

Kidney transplantation

• Adults: The recommended dose is 1 g administered orally or intravenously (over no less than 2 hours) twice a day.
• Pediatrics (3 months to 18 years of age): The recommended dose of the oral suspension is 600 mg/m2 administered twice daily (maximum daily dose of 2 g/10 ml). Patients with a body surface area of 1.25 m2 to 1.5 m2 may be administered capsules at a dose of 750 mg twice daily. Patients with a body surface area >1.5 m2 may be dosed with capsules or tablets at a dose of 1 g twice daily.

Heart transplantation

• Adults: The recommended dose is 1.5 g twice daily administered intravenously over no less than 2 hours or 1.5 g orally twice daily.

Liver Transplantation

• Adults: The recommended dose is 1 g twice daily administered intravenously over no less than 2 hours or 1.5 g orally twice daily.
• Geriatrics (elderly patients): The recommended oral dose is 1 g twice daily for kidney transplant patients, 1.5 g twice daily for heart transplant patients, and 1 g twice daily administered intravenously or 1.5 g twice daily administered orally in liver transplant patients.

Co-administration of acyclovir (Zovirax) or ganciclovir (Cytovene, Vitrasert, Zirgan) and mycophenolate mofetil may cause an increase in blood levels of mycophenolate mofetil and the interacting drug since these drugs compete with each other for elimination via the kidneys.

Antacids containing magnesium or aluminum hydroxide may decrease MPA blood levels. If combination use is necessary, administration of the two medications must be separated by several hours.

Proton pump inhibitors (PPIs) such as lansoprazole (Prevacid), pantoprazole (Protonix), and omeprazole (Prilosec) have been shown to reduce MPA blood levels. This effect may be due to a decrease in mycophenolate mofetil solubility caused by reduced acid secretion in the stomach caused by PPIs.

Cholestyramine (Questran, Questran Light) may cause a decrease in MPA blood levels by binding to it in the intestine and preventing its absorption.

Cyclosporine (Sandimmune) may decrease MPA blood levels. Cyclosporine inhibits multidrug-resistant-associated protein 2 (MRP-2) transporter in the biliary tract, and this prevents the excretion of MPA into bile and elimination from the body.

Mycophenolate mofetil may decrease the effectiveness of some oral contraceptives (birth control pills). Combining mycophenolate mofetil with birth control pills should be done cautiously, and additional contraceptive barriers (such as condoms) should be used.

Sevelamer (Renvela) may decrease MPA blood levels. Sevelamer and other calcium free phosphate binders that are used for treating patients with kidney disease should not be administered with mycophenolate mofetil. If combination treatment is necessary, sevelamer and other calcium free phosphate binders must be given two hours after mycophenolic acid administration.

Norfloxacin (Noroxin) and metronidazole (Flagyl), two antibiotics, may decrease MPA blood levels. Use of these antibiotics with mycophenolate mofetil is not recommended. Other antibiotics that may also decrease MPA levels in the blood are ciprofloxacin (Cipro), amoxicillin plus clavulanic acid (Augmentin), and rifampin (Rifadin, Rimactane).

Probenecid may cause an increase in MPA blood levels by inhibiting its excretion via renal tubular secretion.

Mycophenolate mofetil is excreted in milk of rats. It is not known if it also is excreted in human milk. Due to the lack of conclusive safety data, mycophenolate mofetil should be used cautiously in nursing mothers.

What preparations of mycophenolate mofetil are available?

• Powder for injection: 500 mg
• Capsules: 250 mg
• Immediate-release tablets: 500 mg
• Delayed-release tablets: 180 and 360 mg
• Oral suspension: 200 mg/ml

How should I keep mycophenolate mofetil stored?

• Capsules and tablets should be stored at room temperature, between 15 C and 30 C (59 F and 86 F).
• Oral suspension may be stored at room temperate between 15 C and 30 C (59 F and 86 F) for up to 60 days.
• Oral suspension also may be stored in the refrigerator between 2 C and 8 C (36 F and 46 F), but it should not be frozen.